Internal GPS: for giving the Nobel Prize in Physiology or Medicine – RBC

Nobel Prize this year, John O’Keefe and his wife Mei-Britt and Edvard Moser

Photo: AFP

This year’s laureates, John O’Keefe and his wife Mei-Britt and Edvard Moser, describe a system that allows animals (primarily rats, which were performed their experiments) to navigate in space, relying not on the senses, and the internal representation of space, cognitive map.

The term “cognitive map” proposed in the first half of the XX century American psychologist Edward Tolman, trying to answer the question tantalizing biologists and philosophers for centuries: how to construct a system that allows the brain to navigate in space. He suggested that the area in which the animal moves, somehow projected onto the nerve cells. But that’s exactly how this can happen in his time was unknown. To answer this question, the research needed winners of 2014.

The first of these, John O’Keefe at the end of 1960 began to study the behavior of rats, using cutting-edge at the time the method: it implanted electrodes into the brain of a rodent and recording the electrical activity of individual neurons, or at least of small groups of neurons adjacent to the electrode. In 1971, he published an article with an amazing discovery. In the brain of a rat in the department called the hippocampus, there is a “place neurons” that fire at the moment when she runs through a certain place in a maze. Later, he showed that these neurons are activated each time the animal is returned to the same place. When a rat runs across her famous route, the neurons light up like light bulbs in the chain, one after the other. “By recording the work of a number of nerve cells, you can, without looking at the same animal, tell me where it is and where it is deleted. Brain reflects the presence in the space of a very precise way, “- said a member of the Academy of Sciences Konstantin Anokhin neuroscientist.

This finding strongly promoted neuroscientists, but it still was not enough to explain how animals can navigate in space . Least because the neurons less space than the actual seats – one nerve cell fires in several different locations.

Opening spouses Moser, made 35 years later, in 2005, to complete the picture, which began to take shape in the 1970s. In his laboratory in Trondheim, Norway, they experimented, methodologically similar to the original papers O’Keefe – implanted electrodes in the brain to freely moving rats. They only examined a different area of ​​the brain – ektorinalnuyu cortex associated with the hippocampus. There they found a second important component of the “internal memory” of the space, grid-neurons.

Grid-neurons (blue) located in ektorinalnoy rat cortex. Each neuron is activated when the animal is in a certain space points forming a hexagonal lattice.

Photo: nobelprize.org

Nerve cells found Moser, also responded to the geographical position of the beast. But they are not worked well in a random point and in many different organized hexagonal structure (similar to that which form the mobile cellular towers). When the rat was in one direction, the cage at equal intervals fire gridded. Together with open space previously neurons hexagonal grid modeling in the brain Euclidean surface, theoretically allows to navigate in space entirely without external stimuli. Successive signals from one neuron grid-mark distance, and the sequence of operation of several such cells – the direction of movement.

In the last ten years, neuroscientists have conducted many studies grid-neurons – they took an active part, and John O’Keefe. Firstly, they found out that grids in different layers of the cortex ektorinalnoy have different scale – neurons are activated by different distances. Secondly, they are equally worked in the light and in the dark; thus, it can be assumed that the “internal GPS» runs by itself, without the aid of visual stimuli. Thirdly, in addition to rats, such neurons have been found in bat primates (last year) in humans. At-bats, says Anokhin, the scientists were able to show that the grid described May-Britt and Edvard Moser, a three-dimensional rather than two-dimensional.

«Another amazing side opening Moser, – he adds – in the that these neurons are very strongly associated with memory: the animal remembers the first place, which happened to have appeared “cell space.” Memory is always tied to the space when you recall the events of your life, you always have to answer three questions: “What? When? Where? “. Bundle all three questions is happening in the structures studied by Moser, so their study is so important for the treatment of Alzheimer’s disease and neyordegenerativnyh diseases. ”